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  #16  
Old 04-30-2010, 11:26 PM
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Quote:
Originally Posted by ah-kay View Post
I have read the forum here that I can take the heat shield out and collapse the drive shaft? Is it doable?
I have not read instructions or seen how to do the job.

I just know that on a 123 the Differential is suspended on the Differential Mount; that is all that is holding it in position. Ounce the Differential mount is gone the Differential is only connected to the Axles; since you have already unbolted the Flange.
If on your Car has a similar setup and you need more room I believe it would give you that.

You could try the prying idea as the other member suggested first.

It is your call on how to do the job.

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  #17  
Old 05-01-2010, 03:18 AM
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Hurray, removed the nut and the old seal

I removed the heat shield and dropped the center bearing mounting. The drive shaft joint gives me enough flex and room to drop the shaft at the flange. It is not as difficult as I thought.

But I have a problem:

When I tried to unfold the lip of the lock nut by tapping it with a small screw driver, something unexpected happened. I was tapping it and the nut somehow worked it's way loose. I thought it is supposed to be torqued quite tight. Also I bought a special tool expecting it to be a special nut. But to the contrary, it is just a normal nut like the one used at the wheel axle. I do not even need a socket to remove it, let alone my special tool.

My questions:

1) Is it suppose to be a special nut?
2) How come it was so loose? The last mechanic/factory did not tighten it enough?
3) Should there be a gasket or washer behind the nut? Without any washer, it is possible for oil to leak out through the spline, isn't it?
4) Where can I get a replacement nut, from the dealer?

Thanks
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W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

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  #18  
Old 05-01-2010, 05:05 AM
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I actually just rebuilt one of these, its EXTREMELY easy to do. First off a diff rebuild is not that expensive if you do your own work, pulling the diff is probibally an hour job and rebuilding it is maybie a 4 hour job if you go real slow.

If your just going to replace the pinion seal then you need to make sure the bearing doesnt need replaced as well, if it does then your just throwing money away since if the bearings are bad they are just going to make the seal leak anyways, so check the bearings and you MUST check the rotating torque in both directions with the axles off with a beam type torque wrench. Make sure you write it down, also count the threads or measure how far down the nut is also index the nut to the shaft.

now if your just going to install a new seal its super super easy, remove yoke after marking/measuring rotating torque pry off yoke and pry out old seal, reinstall new seal and yoke with sealant on the splines/nut then torque it down to the indexing to the shaft. (do NOT go past the indexing of the shaft, if you need to preload it more to get the same rotating torque as spec your bearings are worn and need replacing) The way it works is your have a crush sleeve inside that you crush to create preload crush it too much and you wont have preload you will have endplay.

Anyways... if you want to install new bearings its easy as cake on these diffs because they have shims that you simply take out and put the new bearings in and put the shims back in on the same side since the bearings are machined to within .0005 thou of eachother.


its better to be a little loose than tight, if your too tight it would eventually wear the bearings out too quickly. a little loose and as long as your not pounding on it then it wouldnt cause terrible damage until the bearing started to wear in and loosen up.
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Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

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pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.
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  #19  
Old 05-01-2010, 05:15 AM
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Quote:
Originally Posted by ah-kay View Post
I removed the heat shield and dropped the center bearing mounting. The drive shaft joint gives me enough flex and room to drop the shaft at the flange. It is not as difficult as I thought.

But I have a problem:

When I tried to unfold the lip of the lock nut by tapping it with a small screw driver, something unexpected happened. I was tapping it and the nut somehow worked it's way loose. I thought it is supposed to be torqued quite tight. Also I bought a special tool expecting it to be a special nut. But to the contrary, it is just a normal nut like the one used at the wheel axle. I do not even need a socket to remove it, let alone my special tool.

My questions:

1) Is it suppose to be a special nut?
2) How come it was so loose? The last mechanic/factory did not tighten it enough?
3) Should there be a gasket or washer behind the nut? Without any washer, it is possible for oil to leak out through the spline, isn't it?
4) Where can I get a replacement nut, from the dealer?

Thanks
1) Is it suppose to be a special nut? Its not special, doesnt need replaced.
2) How come it was so loose? The last mechanic/factory did not tighten it enough? It was torqued until preload was correct, if that was at 5fp then thats what it was supposed to be.
3) Should there be a gasket or washer behind the nut? Without any washer, it is possible for oil to leak out through the spline, isn't it? Yes it can leak, thats why you put sealant on the splines and nut/washer before you bolt it together.
4) Where can I get a replacement nut, from the dealer? if its not broken then re-use it dont worry about trying to re-stake the nut if you destroyed it. stake it if you can.
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Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.
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  #20  
Old 05-01-2010, 05:55 AM
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If the pinion nut isnt done up with a bucket load of torque then there is something wrong with your calcs of how to do up the pinion nut.

I am very skeptical of the suggestion of doing it up to the same number of turns.

The preload on a pinion is set by the thickness of the spacer shims between the bearings.

How much torque did it take to loosen it? Basic machine design tells you that you will need to torque it to a larger amount than that.

If you have it anything but real tight, expect a diff failure very soon.

The configuration of the pinion bearings is nothing like front wheel bearings.

I strongly suggest you go and talk to a diff re-builder who is doing this sort of work all the time.
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I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
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  #21  
Old 05-01-2010, 11:56 AM
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Guys, he sad it was turned by itself so it was not tight.

This kind of leads to what one of the member siad near the start of the Thread that the Seal often leaks if there is a problem with the Bearing; and, that would also be a resonable explaination as to why the nut was loose.

However, the problem is what is he to do now?

If he installs the Seal he will need something to Torque the nut to.

Or if he decides not to mess withit he had indicated he was open to getting a used Differential.
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  #22  
Old 05-01-2010, 04:34 PM
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Quote:
Originally Posted by Diesel911 View Post
Guys, he sad it was turned by itself so it was not tight.

This kind of leads to what one of the member siad near the start of the Thread that the Seal often leaks if there is a problem with the Bearing; and, that would also be a resonable explaination as to why the nut was loose.

However, the problem is what is he to do now?

If he installs the Seal he will need something to Torque the nut to.

Or if he decides not to mess withit he had indicated he was open to getting a used Differential.
what he needs to do now is to preload the bearings to a certain rotating torque as mentioned in the fsm.

For example, using an impact (would not suggest but it works) run the nut down until you have no endplay on the pinion.

Next measure your rotating torque, you should probibally have 5-10 inch pounds of rotating torque required to turn it, if you dont have that then you need to run the nut down some more.

By the way this is the reason that your seal was leaking, since the tapered bearings allowed the shaft to wobble when the nut came loose. so replaced the seal, use sealant on the splines and then tighten it to the FSM specified rotating torque.

Also, the nut could be torqued to 100foot pounds and still not be at the correct pre-load for the tapered roller bearings so do not try to torque that nut down, you must go by rotating torque and the axles must be disconnected in order to measure it.
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Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.
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  #23  
Old 05-02-2010, 03:40 AM
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What would be the worst scenario?

Thanks for the info.

I do not have the tool to measure the rotational torque. I will put the nut back to where it was and may be a bit more then punch the lip in. Would the pinion shaft has lateral movement when all is said and done? I tried to finger tighten it and I still fell lateral movement of the shaft. The shaft would not go in and out but it seems that it can go sideway ( laterally ). Is it right?

What would be the worst scenario if I did not preload the nut enough or over-tighten it? The job does not seem too complicated now I am almost done but this preload and rotational torque is a bit overwhelming for me.
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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
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  #24  
Old 05-02-2010, 06:16 AM
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The yoke will vibrate on the pinion shaft & so become loose. In the end the diff will be toast & maybe the tail shaft will come off.
As I said before, go talk to some one who rebuilds diffs all the time. I have never known of a pinion nut to be tightened by checking the preload. It is not the same as a front wheel bearing set up.
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I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
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  #25  
Old 05-02-2010, 12:29 PM
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Quote:
Originally Posted by layback40 View Post
The yoke will vibrate on the pinion shaft & so become loose. In the end the diff will be toast & maybe the tail shaft will come off.
As I said before, go talk to some one who rebuilds diffs all the time. I have never known of a pinion nut to be tightened by checking the preload. It is not the same as a front wheel bearing set up.
If a crush collar is used between the bearings the pinion nut is tightened until the desired turning torque for the pinion is obtained. This is very common in newer cars, I'm not sure if Benz has gone to a crush collar or when if they have.
A quick check of my CD repair manual finds 124's and 201s use a crush collar. Likely other models do as well.
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  #26  
Old 05-02-2010, 11:52 PM
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Quote:
Originally Posted by layback40 View Post
The yoke will vibrate on the pinion shaft & so become loose. In the end the diff will be toast & maybe the tail shaft will come off.
As I said before, go talk to some one who rebuilds diffs all the time. I have never known of a pinion nut to be tightened by checking the preload. It is not the same as a front wheel bearing set up.
It is a tough decision.

I would think that if you got the Nut back exactly where it was there would be no differance from the way it was when you took it apart with the exception that you now have a new Seal.

I think I would a lest snug the Nut enough that it would not be loose and be able to turn on by itself.
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  #27  
Old 05-04-2010, 02:42 AM
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I messed up

I think I over-tighten it as I forgot the marking. I think I overtightened the nut by 1 turn, the diff would not turn. I back it off. What damage could be done?

BTW: How to read the diff ratio? Is it stamped anywhere on the casing?
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

Last edited by ah-kay; 05-04-2010 at 02:44 AM. Reason: typo
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  #28  
Old 05-04-2010, 06:33 AM
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When you backed it off did it remain tight? It sounds like the spacer between the 2 pinion bearings may be bad some how. Again as said before there is probably a reason why the pinion seal failed, you may be seeing more symptoms of that.
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I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
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  #29  
Old 05-04-2010, 11:04 AM
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You're getting bad advice here. The spacer between the the pinion bearings is a crush spacer. The pinion nut is tightened until the proper turning torque of the pinion is attained. Over tightening the nut will crush the spacer beyond a usable amount and it should be replaced.
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  #30  
Old 05-04-2010, 11:36 AM
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Quote:
Originally Posted by Chas H View Post
You're getting bad advice here. The spacer between the the pinion bearings is a crush spacer. The pinion nut is tightened until the proper turning torque of the pinion is attained. Over tightening the nut will crush the spacer beyond a usable amount and it should be replaced.
I backed out about a little bit and the diff turns. Is it easy to remove the spacer? I would like to have a look or replace it.

Thanks

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.
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